1. Field of the Invention
The invention relates to a string tensioning part for stringed ball rackets, in particular for tennis rackets and squash rackets.
2. Brief Description of the Background of the Invention Including Prior Art
Frequently, there exists a desire in connection with tennis rackets to change the stringing hardness and, in fact, in particular to increase the stringing hardness.
This may be the case, for example, where the hardness of the balls is changed. In a tennis tournament, for example, the players always use new balls, which are substantially harder than the balls normally used. However, this leads to the situation where, in case of an identical expenditure of force, the balls fly farther and, as a result, pass the baseline more frequently. In view of the short time available, an adaptation of the mode of play to the changed situation, is in most cases no longer possible.
As is known, the hardness changes in the course of time in connection with older stringing of rackets. Depending on the material and original hardness, this occurs at different time lapses. The stringing hardness can thereby decrease to such an extent that, based on the resulting trampoline effect, a controlled game is no longer possible.
The hardness decreases in case of catgut stringing, if the strings have become humid. Even in case of an otherwise completely perfect and hardly worn stringing, an expensive restringing is required.
The hardness decreases particularly rapidly in case of a first stringing of a new frame. It can occur in such cases that, in case of an original hardness of 25 kg, after one week there remains a hardness of only 20 kg.
Finally, it is desirable, in case of different floor surfaces of the courts, that the stringing hardness be adapted in each case. A "fast" hall floor surface, for example, requires a harder stringing.
Special tennis rackets have already become known, where the tension of the center longitudinal strings can be changed by turning and rotating of a set screw at the handle end. Such rackets are, however, relatively expensive and have not found wide-spread acceptance.
There are further known plastic platelets, which are inserted between the crossing points of the longitudinal and cross strings. These platelets are to decrease the wear generated by the friction of the strings at the crossing points. The platelets effect, in case of a large-surface application, also a slight increase of the stringing hardness. However, the time-consuming insertion of a large number of such platelets in order to achieve a noticeable increase in the tensioning is a serious disadvantage.